The process of the present invention relates to the upgrading of lower alcohols to form higher molecular weight alcohols. More particularly, the process of the present invention relates to the contacting of lower molecular weight alcohols such as methanol, ethanol and propanol with a solid reaction promoter composition to form alcohols having higher molecular weight, i.e. a greater number of carbon atoms per molecule.
Lower alcohols are easily produced by a variety of methods. Methanol is produced from natural gas or coal partially oxidized to form carbon monoxide and hydrogen, followed by catalytic conversion to methanol. Ethanol and propanol can be produced by direct hydration of ethylene and propylene, respectively. Ethanol can also be formed by the fermentation of sugars.
Methods have been sought for the production of higher molecular weight alcohols from lower alcohols. The higher molecular weight alcohols are useful as solvents, fuels, gasoline extenders, and intermediates for other chemical products.
It has been shown that the homologation of lower alcohols such as methanol can be carried out in the liquid phase under high pressure with the introduction of synthesis gas, or carbon monoxide and hydrogen, in the presence of a Group VIII catalyst such as cobalt, nickel, and ruthenium. Variations of this process are described in U.S. Pat. Nos. 3,248,432; 3,285,948; 3,387,043; 4,126,752; 4,133,966; 4,150,246; 4,168,391; 4,233,466; 4,205,190; 4,111,837; 4,171,461 and 4,239,925. These processes generally require the presence of a corrosive promoter such as iodide compounds.
In the 1940's, Yogryoji Negishi investigated the formation of butyl alcohols in the presence of calcium carbide. In one set of experiments, mixtures of carbon monoxide and hydrogen were contacted in the presence of a methanol catalyst and calcium carbide to form butanol. In another set of experiments, ethanol and hydrogen were contacted with a paste consisting of 100 grams of calcium carbide, 400 grams of carbonate or calcium oxide, and 1,000 grams of a paste vehicle such as lubricating oil to result in the isolation of butanol, and possibly hexanol.
U.S. Pat. No. 3,972,952 describes the vapor phase conversion of methanol and ethanol to higher linear primary alcohols by heterogeneous catalysis. The catalyst composition utilized was made up of particles of an inert, high surface area support such aluminum oxide, impregnated with inorganic base promoters such as oxides, hydroxides, or basic salts of alkali metals or alkaline earth metals, and a platinum group metal. The process was carried out in the presence of synthesis gas at elevated pressure.
It is therefore an object of the invention to upgrade lower alcohols, particularly methanol, to form higher molecular weight alcohols.